Sump Pump in Patio / Yard Drains

We have very little elevation change between our house and a roadside drainage ditch. I've got about 8 inches, maximum, to work with across a 40 foot span. Obviously, once you trench down at least a foot, you're in trouble. It makes it very difficult to get the proper slope on any kind of pipe across the 40' run we need.

So, I figure we need to drain a concrete patio which is surrounded by a block wall in one of two ways:

- Install a channel drain whose outlet flows into a catch basin and is then pumped vertically upward over the wall before leading toward the property edge.

- In lieu of the channel drain, install a sump pit with a grated cover on it (to serve as a catch basin) in the corner toward which the patio slopes. Again, pump the water vertically upward over the wall and toward the roadside.

What are the major things to be concerned with in this project? Any obvious roadblocks I will encounter?

Also, I'm concerned with how to terminate the PVC once I get to the ditch. It is not a concrete ditch - the roadway is approximately 2 feet higher than the yard and there is no curb. The ditch is just made of earth. I'm concerned that no matter what I do the end of the pipe will ultimately become filled with sediment as erosion takes its natural course. How can I terminate the line to avoid this?

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Sump Pump in Patio / Yard Drains

I don't think it matters where you put the dry well although it would be better if the water drains from the patio to the dry well by itself and also the dry well is not close to the house. Then you pump from the dry well to wherever if the dry well fills up.

To avoid the need for a grating in the patio you could drill a hole in the patio side wall to install a gravity flowing drain pipe to the dry well just outside.

Have the drain pipe out front enter the drainage ditch from the side rather than at the bottom. This will require more careful sloping but will also be easier to clean out periodically.

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Sump Pump in Patio / Yard Drains

Thanks for the reply! That's basically how things work now. Wtet flows off the patio in one corner through a hole via slope and gravity and enters a schedule 40 PVC drain to get it to the drainage swale. If it really pours though and the water level in the swale rises near the crest the pipe backs up and water pours onto the patio. I'm waiting on a 4" flapper backflow to arrive to help that issue.

We have clay soil so a traditional dry well likely won't work. I don't know how deep the clay is - I've only dug down about 2 feet and I was still in it. Draining into a catch basin underground will allow me more potential for a passive flow system and then I cam pump back up to discharge.

I've buried 4" pipe but nothing as small as 1-1/2". Any special considerations to know about for the smaller diameter?

Sump Pump in Patio / Yard Drains

Ever think of a french drain from the patio to the road, no pumping required.

Mark

Unfortunately it can't be done. From the yard surface to the bottom of the drainage ditch there is only roughly 8" of elevation change (across 40') so we have less than a 2% grade.

A french drain pipe is 4" in diameter so if we dig down 8" and cover it with 4" of soil there's no way we can slope it. We're already level with the bottom of the swale at that point. You'd also be at the frost line and in these cold Virginia winters that would be a bad thing.

The swale ties into the neighborhood drainage system and if we were to try to make it deeper we would be below the swale depth of the neighbors yard.

To have been here 40 odd years ago when they graded this subdivision...

Sump Pump in Patio / Yard Drains

So, next hurdle, if we're 20' from the house obviously the cord from the sump pump won't work. We were going to get the Zoeller M53 pump and cutting the cord end voids the warranty on it. Do we just have a receptacle ran out next to the sump pit?

Sump Pump in Patio / Yard Drains

Quote:

Originally Posted by Jackofall1

I was thinking more of a 1% sloped trench with no pipe, just pee gravel

Mark

It's a possibility but if the trench fills to capacity there would be nothing stopping the water from running back up onto the patio. I guess that's the only concern with having an open system like that.

I'm trying to figure out a long-term way to put a flapper check valve at the exit point for the patio. If I can figure out a way to fit that in then a passive drainage system without piping would probably be effective.

Sump Pump in Patio / Yard Drains

Quote:

Originally Posted by JustADoc

It's a possibility but if the trench fills to capacity there would be nothing stopping the water from running back up onto the patio. I guess that's the only concern with having an open system like that.

I'm trying to figure out a long-term way to put a flapper check valve at the exit point for the patio. If I can figure out a way to fit that in then a passive drainage system without piping would probably be effective.

The way I see it Doc, is, if a gravity open drain filled to capacity the surrounding area would also be underwater, if the entire area is underwater so is the pumped system.

Mark

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Sump Pump in Patio / Yard Drains

The patio slab is sloped toward the corner that you see in the photo with the notes on it. It passively drains through an opening, down into this PVC pipe, and out to the roadside swale.

I'm currently toying with how to terminate this PVC pipe. I'm probably going to put a 45 degree sweep on it, another length of pipe, and have it come directly into the swale. We're below surface level right now so a pop-up emitter isn't an option and I'm not sure the pipe slopes enough to utilize one.

Any suggestions on how to best keep the pipe from becoming clogged with sediment on the end over time? I'm thinking about just concreting around it to give it some mass and putting a splash block under it to help with erosion where it empties.

Is the planned location for the 4" flapper backflow valve the best bet? We had considered putting it further up the pipe but the idea is if water ever backflows into the pipe we want it to stop but we would also like to have some length of pipe that water can still flow into from the patio.

There are also some other photos so you can see what I'm battling with. The one cropped photo shows you how level this lot is. There's nearly no grading from the house to the swale and no potential to correct the grading. The house should have been built at least 3 block higher.

Sump Pump in Patio / Yard Drains

If it really pours though and the water level in the swale rises near the crest the pipe backs up and water pours onto the patio. I'm waiting on a 4" flapper backflow to arrive to help that issue.

We have clay soil so a traditional dry well likely won't work. I don't know how deep the clay is - I've only dug down about 2 feet and I was still in it. Draining into a catch basin underground will allow me more potential for a passive flow system and then I cam pump back up to discharge.?

Yes.

Put in the dry well although it will function as a sump as opposed to a real dry well (absorption facility). So you have a gravity flow from the patio to the dry well and another gravity flow from the dry well to the front drainage ditch. The sump pump gets the water from the (lower) end of the first gravity flow to the (higher) start of the second gravity flow.

You do not want a backflow valve out front. This will almost surely result in the pipe freezing and cracking in winter. The drain pipe itself must have slope to drain by gravity. Given the existing grading, the PVC should not begin in the dry well but instead should begin higher and water is put into it by the sump pump.

Is there any surface slope at all from just outside the patio to the drainage ditch? Then you can put the drywell near the patio and pump the water out onto the surface and the water will then flow to the ditch by itself. No PVC drain pipe going out to the front.

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Sump Pump in Patio / Yard Drains

Quote:

Originally Posted by AllanJ

Yes.

Put in the dry well although it will function as a sump as opposed to a real dry well (absorption facility). So you have a gravity flow from the patio to the dry well and another gravity flow from the dry well to the front drainage ditch. The sump pump gets the water from the (lower) end of the first gravity flow to the (higher) start of the second gravity flow.

You do not want a backflow valve out front. This will almost surely result in the pipe freezing and cracking in winter. The drain pipe itself must have slope to drain by gravity. Given the existing grading, the PVC should not begin in the dry well but instead should begin higher and water is put into it by the sump pump.

Is there any surface slope at all from just outside the patio to the drainage ditch? Then you can put the drywell near the patio and pump the water out onto the surface and the water will then flow to the ditch by itself. No PVC drain pipe going out to the front.

You basically summarized my intentions. I do want all this to begin from a channel drain as I think this whole "drain out a hole into a catch basin" thing is rubbish. She needs something with more surface area to capture water AND if this existing PVC drain backs up for whatever reason it will catch the backup and get it away.

There is slope from the exit point on the patio to the inlet of this drain. It has a concrete splash block type structure it flows down and then into the inlet grate.

If we pump onto the surface of the yard directly it would probably only result in a soggy yard. There's some natural slope but no water would percolate through the ground. It's about 4" of topsoil and then at least 2' of very very heavy clay.

The only water this and any other drain should catch is the amount that falls on the patio in the 2' span that isn't covered by the roof. It should never see copious amounts of water. The issue is in its inherent failure. What happens is as the water table rises and thus the water in the swale rises then the pipe level becomes even with the water table level. Water backs up the pipe, rushes onto the patio through the hole, and floods her basement.

Sump Pump in Patio / Yard Drains

The catch basin (or dry well) collects water running off the patio but is set up so water already on the lawn cannot go in. ALso the PVC pipe to the front does not connect to the catch basin

A sump pump in the catch basin comes on when the catch basin fills up. The primary way out of the catch basin is via the sump pump. At this point in the discussion I will leave it up to you as to where the sump pump will discharge the water. For example the PVC pipe from the front can have an elbow to point it straight up and it ends a few inches above ground level and the sump pump dumps into that.

This way water backing up the PVC pipe can't get back onto the patio.

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Sump Pump in Patio / Yard Drains

The catch basin (or dry well) collects water running off the patio but is set up so water already on the lawn cannot go in. ALso the PVC pipe to the front does not connect to the catch basin

A sump pump in the catch basin comes on when the catch basin fills up. The primary way out of the catch basin is via the sump pump. At this point in the discussion I will leave it up to you as to where the sump pump will discharge the water. For example the PVC pipe from the front can have an elbow to point it straight up and it ends a few inches above ground level and the sump pump dumps into that.

This way water backing up the PVC pipe can't get back onto the patio.

That's actually a very novel idea. I like the way you think. I'm going to toy with that idea and I'll come back with what I plan.

Zoeller voids a pump warranty if you cut the electrical cable. Should I just mount an outlet on a post above ground level where the sump is and plug it in? Not sure how plumbers would handle that situation electrically other than doing that.

Sump Pump in Patio / Yard Drains

Yes, install an outlet with a weathertight cover near the sump (catch basin; dry well).

(Nowadays, all outdoor outlets need a weathertight cover; you can get covers that have a slot in the bottom for a cord that is plugged in.)

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__________________(One morning on WRKO Radio) The tub's not clean! Let's remodel the bathroom.
(One afternoon on WRKO Radio) It's time for an oil change. I'm going to trade in the car for next year's model.